A core of a nuclear reactor is composed of a plurality of fuel assemblies which require periodic removal for refueling or repair. These fuel assemblies are typically composed of a group of fuel rods incorporated with plates which maintain the fuel rods in proper proximity to allow a cooling fluid to flow around the rods to maintain the rods at a proper temperature. Consequently, the fuel assemblies are usually surrounded by various auxiliary structures such as baffles, which direct cooling flow for optimum efficiency to cool the fuel rods. It is typical for the reactor core fuel assemblies to be aligned in the reactor vessel by lower and upper assemblies known as internals packages.
During refueling, the upper reactor internals are lifted out of the reactor housing. Presently, it is difficult to determine if one of the fuel assemblies, during lifting, has become entangled with the reactor upper internals structures. If this occurs, a fuel assembly may be pulled out of the core and dropped. Thus, the fuel assembly or upper internals may be damaged, requiring costly and time consuming repairs.
Prior attempts to inspect the upper internals package during lifting utilized a video camera. The distance of lift required to perform the inspection, generally above the reactors upper flanges, could cause damage before the entanglement was detected. Consequently, other inspection methods and apparatus are required.